cut·lass also cut·las (k?t?l?s)n.1. A short heavy sword with a curved single-edged blade, once used as a weapon by sailors.2. Caribbean A machete.[French coutelas, from Old French coutelasse, probably augmentative of coutel, knife, from Latin cultellus, diminutive of culter, knife; see skel- in Indo-European roots.]American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.